This invention relates to cased telescoped ammunition comprising, in part, a long rod fin stabilized projectile. In particular it relates to a sabot means for guiding the projectile down a rifled barrel.
In the past saddle sabots have been used to guide a long rod fin stabilized projectile down a rifled barrel. The saddle sabot is shaped, as the name implies, similar to a saddle with a front and rear stabilizing disk. The sabot engages and surrounds the midsection of the projectile, the front and rear stabilizing disks being positioned such that they support the front and rear portions of the projectile. This enables the sabot to prevent the projectile from oscillating when it is fired.
As long rod penetrators are typically launched from rifled barrels they pick up some spin as they travel down the barrel. For a long rod projectile a high rate of spin is detrimental. A saddle sabot has stabilizing rings and will not readily pick the rifling of the barrel, as the stabilizing rings ride the bore or barrel and not the rifling. If the projectile were to pick up rifling (and thus spin) there are two immediate concerns that are realized. The first is that the fin stabilized projectile will be damaged due to the high number of revolutions per minute imposed upon it. The second is that the sabot will become deformed while picking up the rifling. This will cause the projectile to leave the bore of the barrel at an increased angle relative to the axis of the bore and thereby become inaccurate.
Although a saddle sabot will support the long rod projectile while traveling down the barrel it has a disadvantage. A saddle sabot has the obturator, the pressure sealing surface, on the rear stabilizing ring. The amount of volume left for propellant is therefore restricted. This affects the performance of the device and forces the manufacturer to use a consolidated propellant to reach performance goals. A consolidated propellant is a propellant that is formed to the cartridge to increase the amount of energetic material present. A granular propellant is preferred, as it is more repeatable and involves fewer total steps in loading of the cartridge.
A puller sabot is an arrangement designed with an obturator located forward of the penetrator's center of gravity. A puller sabot is in essence a saddle sabot with out the rear stabilizing disk. This increases the volume available for propellant and increases the performance. Puller sabots of prior art however, lack proper guidance of the projectile while traveling down the barrel. As stated before this leads to oscillations and possible damage to the projectile prior to exiting the barrel. U.S. Pat. No. 4,444,114 issued to Bisping et al., teaches a method of supporting a long rod fin projectile yet still has the advantages of a puller sabot. This sabot uses a plurality of ribs to support the projectile as it travels down the barrel. These ribs could possibly engage the rifling of the barrel and start the projectile oscillating, destroying the projectile in-bore.
Prior designs show puller sabots and saddle sabots both of which serve a purpose. However, no prior art has been able to properly stabilize a long rod finned projectile as it travels down a rifled barrel, while still providing maximum volume for propellant in the cartridge.